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AD5111 is broken?

Hello.

I designed our product by applying AD5111 (10K, Up/Down).
It worked normally once or twice, but it is currently fixed at A-W 45 ohm and W-B 9.8K ohm, and does not respond to any commands.
Sometimes when power is applied again, it becomes A-W 9.8K ohm, W-B 39 ohm.
The strange thing is that the resistance of A-B is measured around 9.8K.
Judging by the resistance value, it doesn't seem like a malfunction. What's the problem?

PS - Of course, other AD5111s are operating normally when tested by connecting them to the same signal port.

Thanks in advance for your kind reply.



Title errata correction
[edited by: Nun2K at 5:38 AM (GMT -4) on 15 Apr 2022]
  • Please share the circuit diagram and the power supply sequencing details.

    Does the part respond to U/D state?

  • Hi, vsethia.

    Thank you for your kindness.
    I answer your question as follows.

    1. Please share the circuit diagram and the power supply sequencing details.

    -> Power is supplied directly from AD/DC 5V power.
    The sensor signal(A/sens_2, W/sens_1, B/sens_3) connection is controlled using the photo relay (control line SW_COMP_VDIV-FCC).
    (Of course, SW_COMP_VDIV-FCC is maintained High level at initial and normal.)

    Can the power supply sequencing have a critical effect on the behavior of a part?

    2. Does the part respond to U/D state?

      -> In U/D state, parts do not respond.

  • Until the AD5111 is powered up, the relay control SW_COMP_VDIV_FCC is set to high (5V) and no signals are applied on A, W, B terminals. Is that correct?

    What are the voltages on the sens_1, sens_2 and sens_3 signals?

    What is the SW_COMP_VDIV_FCC when you try to turn on the relays.?

    What is the state of /CS and SCLK when you try to update the wiper position?

  • Until the AD5111 is powered up, the relay control SW_COMP_VDIV_FCC is set to high (5V) and no signals are applied on A, W, B terminals. Is that correct?

      -> Yes.

    What are the voltages on the sens_1, sens_2 and sens_3 signals?

      -> sens_2 = 0.2V, sens_3 = 0V (GND), sens_1 = 0.193V ~ 0.027V

    What is the SW_COMP_VDIV_FCC when you try to turn on the relays.?

      -> If it means the control signal voltage level of SW_COMP_VDIV_FCC at relay turn on, it is changed to High(5V) -> Low(0V).

          On the other hand, it is changed to Low(0V) -> High(5V) at relay turn off.

    What is the state of /CS and SCLK when you try to update the wiper position?

      ->  /CS is Low and /CLK is High -> Low

    I have a question.
    If a signal is connected to another port before power is applied to VDD/GND, can AD5111 be broken?

  • On your last query, please elaborate with a circuit diagram.